It is well known that the normal bacterial flora in the upper respiratory airways is of significant importance in preventing overgrowth of pathogenic bacteria and subsequent infection. Most of the bacteria of the normal flora consist of alpha haemolytic streptococci (AHS). It has been shown that one of the most important mechanisms used by AHS in order to inhibit growth of the rhinosinusitis and otitis media pathogens, is to produce considerable amounts of hydrogen peroxide, H2O2 [1].
The hydrogen peroxide also contributes as a substrate for lactoperoxidase (LPO), a member of the non-specific defence system of the nasopharyngeal mucosa. Lactoperoxidase is dependent of hydrogen peroxide for production of hypothiocyanate, OSCN−, a more potent antibacterial substance. The normal bacterial flora including AHS and the human mucosa have a natural protection against both hydrogen peroxide and hypothiocyanate [2].
While the use of a hydrogen producing enzyme in ointment around the skin and nasal orifices for treatment of staphylococci has been disclosed previously, this is a treatment directed towards the bacteria of the skin flora, a parallel to the hydrogen peroxide containing ointment Microcid™.
EP 1 490 096 disclose the use of a hydrogen peroxide producing nasal spray for treatment of otitis media, preferably in children. However, while there are several antibiotics intended to treat otitis media, there is no proved active treatment against the common cold caused by Rhinovirus.